Method for cooling a traction battery of an electrically drivable vehicle, and cooling arrangement for carrying out the method

Abstract

In a method for cooling a traction battery of an electrically drivable vehicle, a refrigerant is used as cooling medium, and in a mass flow of specified magnitude is led along the traction battery through at least one channel. The at least one channel is in heat-conducting connection with the traction battery. It is proposed that an available cooling power (P V ) for cooling the traction battery is determined, wherein as a function of the available cooling power (P V ), the magnitude of the mass flow of the refrigerant is regulated in such a way that either no cooling power (P actual ) is delivered to the traction battery, or the delivered cooling power (P actual ) in each case assumes one of multiple cooling power stages (I, II) as a function of the available cooling power (P V ).

The invention claimed is: 
     
       1. A method for cooling a traction battery of an electrically drivable vehicle, the method comprising:
 utilizing a refrigerant as cooling medium, 
 directing the refrigerant, in a mass flow of specified magnitude, along the traction battery through at least one channel, wherein the at least one channel is in heat-conducting connection with the traction battery; 
 determining an available cooling power for cooling the traction battery; and 
 regulating the magnitude of the mass flow of the refrigerant as a function of the available cooling power, such that either:
 no cooling power is delivered to the traction battery, or 
 cooling power in each case is delivered to the traction battery, wherein the cooling power assumes one of multiple cooling power stages as a function of the available cooling power. 
 
 
     
     
       2. The method according to  claim 1 , further comprising dividing the available cooling power for the battery cooling into multiple power ranges, wherein at least one lower limit value is associated with each power range, and each power stage corresponds to the lower limit value of a specific power range. 
     
     
       3. The method according to  claim 2 , wherein the total amount of power stages is three predetermined power stages. 
     
     
       4. The method according to  claim 3 , further comprising dividing the available cooling power for the battery cooling into three power ranges, wherein:
 in a first power range, the available cooling power is less than 1 kW, 
 in a second power range, the available cooling power is greater than 1 kW but less than 3 kW, and 
 in a third power range, the available cooling power is greater than 3 kW, 
 wherein a first power stage does not cool the traction battery at all, a second power stage cools the traction battery with 1 kW, and a third power stage cools the traction battery with 3 kW. 
 
     
     
       5. The method according to  claim 2 , further comprising setting the cooling power to be delivered in each case in the cooling power stages as a function of the temperature of the traction battery, wherein the ratio of the cooling power to be delivered in the cooling power stages remains constant. 
     
     
       6. A cooling arrangement for carrying out the method according to  claim 1 , wherein the traction battery has multiple battery modules, the method comprising:
 directing a refrigerant through at least two channels along the battery modules, perpendicularly with respect to the battery modules' longitudinal orientation, wherein the at least two channels are in heat-conducting connection with the battery modules, 
 directing the refrigerant in at least one supply channel along the battery modules in a first direction to at least one connecting element, 
 returning the refrigerant in at least one return channel along the battery modules in a second direction, wherein the first and second directions are oriented in parallel to one another, and wherein the connecting element fluidically connects the at least one supply channel to the at least one return channel, and 
 operating the cooling arrangement in an operating mode in which the traction battery is cooled solely in the power stages, wherein in each power stage the refrigerant either:
 has already completely evaporated in the area of the connecting element after being led through the at least one supply channel, 
 is completely evaporated in the area of the connecting element, or 
 is not evaporated until it has completely returned via the at least one return channel. 
 
 
     
     
       7. The cooling arrangement according to  claim 6 , wherein in that the at least two channels are each in heat-conducting connection with the battery modules of the traction battery via a heat-conducting contact surface in such a way that an area ratio of the total contact surface of the at least one supply channel to the total contact surface of the at least one return channel of 1:1, 1:2, or 2:1 results. 
     
     
       8. The cooling arrangement according to  claim 7 , wherein in that dimensions of each channel and of each battery module are the same, and the number of the at least one supply channel, the method further comprising selecting a number of the at least one return channel in such a way that a ratio of the at least one supply channel to the at least one return channel is 1:1, 1:2, or 2:1. 
     
     
       9. The cooling arrangement according to  claim 8 , further comprising selecting one supply channel and two return channels. 
     
     
       10. The cooling arrangement according to  claim 8 , further comprising selecting two supply channels and one return channel. 
     
     
       11. The cooling arrangement according to  claim 6 , further comprising cooling the traction battery in the operating mode solely in two power stages. 
     
     
       12. An electrically drivable vehicle, characterized by at least one cooling arrangement according to  claim 6 .